If attacks similar to those that occurred earlier Thursday in London happened in the United States, most cell phone users would have trouble getting emergency crews to find them, according to experts.
Despite efforts after the September 11, 2001, terrorist attacks to beef up mobile service so cell phones could be used to help track down people, "we're in a sad state of affairs in the United States," says Jack Gold, an independent analyst for J. Gold Associates in Northboro, Massachusetts. "If we faced a major disaster like London and had to locate injured people on cell phones today, maybe one or two could be located, but the system couldn't handle hundreds of calls."
"Location [tracking] is not an easy thing to do," he says.
Part of the problem in using emergency 911 (E911) wireless services would be too many callers making simultaneous calls at the same time, Gold says. Also, technical complexities and costs have slowed efforts by wireless carriers to implement automatic systems that could be used to locate cell phone callers, Gold and other experts say.
"It's a very difficult problem given the wireless infrastructure," Gold says. "Don't count on being rescued with your wireless phone unless you know exactly where you are" and can tell an emergency operator clearly.
Colleen Boothby, an attorney with Levine, Blaszak, Block & Boothby in Washington, D.C., who regularly appears before the Federal Communications Commission, says wireless E911 is "a lot better than it was five years ago" but agrees that the service is not where public officials want it to be because of some "very technical issues."
There are two primary ways of finding a person using a cell phone who dials 911: network-based solutions and handset-based solutions, according to an FCC report to Congress on April 1. Another method relies on a combination of the two. (Read the PDF of the FCC report.)
Network solutions rely on equipment that captures the signal from a cell phone, including one approach called Angle of Arrival, which measures the direction of a signal at three cell sites and then uses that data to calculate a user's location. Other methods rely on the timing of a signal's arrival at different towers or a comparison of its "signature" based on echoes from known buildings and landmarks.
A handset solution means the cell phone is equipped with a Global Positioning System chip set used to communicate with satellites that can transmit a user's location.
Both methods have technical limitations, Boothby says. Rain and snow can interfere with satellite signals, and network systems tend to work best in two dimensions--signal width and length--but not height. That would make it hard to find an office worker's floor in a tall building.
According to Gold and Boothby, all cell phone makers today manufacture GPS-enabled phones. But Gold estimates that only 1 percent of all cell phones in use have GPS chips.
The April FCC report to Congress focused on small wireless carriers, where the biggest concerns about E911 deployments have been raised. Of 390 smaller carriers, only 10 were providing E911 services as of April. Over the last five years, the FCC has granted 173 requests for waivers from E911 requirements by the smaller carriers.